LG K51 falls in the mid-range. It offers most of the useful smartphone features at a budget price. K51 is the successor to LG K40 which itself is a decent mid-ranger.
If the MetroPCS/T-Mobile smartphone lineup is considered, the LG K51 falls between Aristo 5 & Stylo 6. In this post, we are going to find out the pros and cons of LG K51. Let’s also check out, how does it compare to K40, Aristo 5 & Stylo 6 –
LG K51 Pros & Cons
Let’s begin with the Pros –
LG K51 PROS
1. Big Screen with 19.5:9 Aspect Ratio

The highlight of K51 is its big 6.53 screen with a notch. The notch design offers more screen estate in less space. K51’s screen is bigger than Stylo 5 but smaller when compared to Stylo 6.
K51 looks like a phone from the higher segment when kept beside K40. K40 comes with a 5.7 inches screen. It is smaller in size but fits nicely in hand.
2. Android 10 out of the box
Except for Boost Mobile K51, the rest of the variants come with Android 10 out of the box. The K51 Boost Mobile comes with an Android 9 operating system.
LG Aristo 5 & Stylo 6 are also running on Android 10.
3. Triple Rear Camera Setup

LG K40 comes with a single 13MP camera on the rear.
On the other hand, K51 offers triple cameras on the back. Apart from the main 13MP camera, there is a 5MP wide-angle (115°) camera & a 2MP depth sensor for the bokeh effect.
4. Wifi Calling Support
LG K51 also offers Wi-Calling. However, it’s is a carrier dependant feature.
Boost Mobile, MetroPCS, T-Mobile K51 support Wi-Fi calling. I’m not so sure about the Verizon K51.
5. Expandable Memory
The internal storage space on K51 is 32GB. Almost half of this space is used by the system memory. The usable storage space is hardly 16 GB.
The good thing is we can expand the storage space using a memory card. It supports micro SD card up to 256GB.
6. Headphone Jack 3.5 mm
Nowadays many of the flagship devices are done away with the 3.5 mm headphone jack.
Luckily, K51 comes with a headphone jack located at the bottom as shown in the above picture.
8. Adoptable Storage Support
The K51’s low internal memory can be expanded with an SD card. However, the apps and games still occupy the internal storage space.
The solution to this problem is the adoptable storage feature. We can move the apps to SD card on K51 and make it the default storage space for apps and games.
Please refer to the above screenshot. The SD card is partitioned into 2 parts. One part is being used as internal storage.
7. Multitasking with Dual Screen & Pop-up window
LG K51 offers multitasking just like a computer.
There are 2 modes of multitasking. Using the multi-window feature we can split the screen into 2 and use 2 apps at once.
Using the pop-up window feature, we can run an app in the mini-window format as shown above. We can minimize this app and launch a new pop-up window. This way we can work on many apps at once.
LG K51 Dual Screen & Pop-up Window
8. LED Notification Light
The notification light was also offered on LG K40. K51 also offers Blink LED to notify missed calls, messages, and app notifications.
9. USB Type-C Charging Port
The Type-C USB Port is offered for the first time in LG KSeries. LG K40 comes with a Micro USB Port.
10. Sensors
All the useful sensors are offered by LG K51.

It comes equipped with Accelerometer, Ambient Light Sensor, Digital Compass (Magnetometer) & Gyroscope (VR Headset Compatible).
11. USB OTG Compatible
I connected a Pen Drive & Mouse to my K51 using an OTG adapter. Both worked fine.
We can increase the mouse pointer size in the accessibility settings.
12. Fingerprint Scanner
The fingerprint scanner in K51 is located at the back of the phone as shown above.
We can add multiple fingerprints for screen unlocking.
LG K51 CONS
1. Poor Hardware

If you’ll observe closely, you’ll see a lot of cost-cutting on LG K51 as compared to its predecessor K40.
First of all, LG has opted for the cheaper entry-level Mediatek Processor for K51. Until now, every K series phone came with a Snapdragon Processor. Mediatek CPU’s are comparatively cheaper.
2. No Fast Charging Support
Quick Charge support is getting quite common nowadays. It’s a must-have feature. The Fast Charging support is still not offered on LG K series smartphones.

The fast-charging icon on LG Stylo 6 can be seen in the above screenshot. A battery with a lightning symbol.
3. Low Screen Resolution
The Full HD screen resolution is offered on LG Stylo series smartphones which fall in a segment higher than the K Series.
The HD resolution on K40 looked fine because of the small screen size. However, for a big 6.5 inches screen, the HD resolution looks quite pixelated. K51 offers a screen resolution of 1560 x 720 pixels with a pixel density of around 264 PPI.
4. Root – TWRP – Bootloader Unlocking – Custom ROM status
LG K51 comes with a locked bootloader that cannot be unlocked. The “bootloader unlock command” simply reboots the phone.
With a locked bootloader, we cannot flash a custom recovery such as TWRP. Without TWRP, we cannot flash Magisk or SuperSU root file.
LG K51 cannot be rooted as of now.
LG K51 Root, Bootloader Unlock, TWRP
5. Not compatible with MHL / HDMI Alt Mode
You may be hoping to mirror your K51 screen on the TV using an HDMI / MHL adapter. Don’t keep your hopes high. The HDMI alt mode support is only offered on the flagship LG devices belonging to V & G Series.
LG K51 is not compatible with HDMI Alt Mode/MHL/Slimport.
6. Face Recognition/Unlock not supported

It quite surprising that the face unlock feature is removed on LG K51. Face recognition was offered on K40. You can refer to the above screenshots.
Face unlock is more convenient than Fingerprint in my opinion.
7. Not compatible with Fortnite
The limited 3 GB RAM on LG K51 makes it incompatible with Fortnite. K51 could have been a good gaming phone if offered with at least 4GB RAM.
8. Does not support 5G
The 4G technology has grown old by now. It will be obsolete in the coming years.
To remain future proof we need to opt for 5G phones. Unfortunately, as of now, only the LG flagship devices offer 5G technology. K51 being a mid-range phone lacks 5G support.
9. Low internal storage & RAM
Being a mid-range phone I expected at least 4GB RAM & 64GB storage from K51. The 3GB – 32GB combination seems quite insufficient as per today’s standards.
10. Does not support Wireless Charging out of the box
Wireless charging is an addiction once you get used to it. Being a mid-range phone, K51 lacks Qi charging.
However, we can make it Qi-enabled. Learn how to make it wireless charging capable –
LG K51 Wireless Charging – How to Enable
11. No “Cast” option for Screen Mirroring
For wireless screen mirroring the phone should be Miracast enabled.
I searched for the “Cast” option on K51, but couldn’t find it anywhere.
We can still mirror our K51 screen to the TV using alternate options. Learn how to mirror LG K51 to Chromecast, Roku, Fire Stick, Samsung Smart TV, etc. –
12. Non-Removable Battery
The removable battery was last offered on LG K20, as far as LG K Series is concerned. This way we can have a spare battery for emergency situations.
Unfortunately, K51 comes with a non-removable battery.
13. Lacks IR Blaster
With the IR blaster support, the phone can be used as an all-in-one remote for all home appliances.
LG K51 lacks an IR blaster.
14. Durability
The front and back of the LG K51 is all glass. Once fall and the glass may shatter. K51 doesn’t use a Gorilla Glass. You should always use it with a cover and screen guard.
You should also keep it away from the water as it’s not waterproof.
15. No Selfie Flash
One more useful feature omitted from K51 is the Selfie Flash. The Front camera flash was offered on LG K40 as evident in the above picture.
On LG Android 10, the default mode of navigation is using Gestures. We don’t get the usual navigation bar with the Home, Back & Recent Apps buttons. This is quite annoying.
To good thing is, we can change these settings can get back the navigation bar with the home touch buttons –
LG K51 Home & Back Button/How to Close Apps
17. Lacks NFC / Android Pay

One very prominent & significant feature removed from the LG K51 is NFC / Android Pay. The omission of NFC makes me wonder, whether the K51 is an upgrade or downgrade from K40.
I couldn’t find NFC anywhere on LG K51.
CONCLUSION
Going through the Pros & Cons of LG K51, let’s see where does it fall as compared to K40 –
These are areas where K51 beats K40
- Android 10
- Bigger display with more screen estate
- USB Type-C Port
- Rear Triple Cameras
In these fields, K40 excels K51 –
- NFC Support
- Front Camera Flash
- Face Recognition for screen unlocking
Keeping the above features in mind, you can decide whether K51 is the right upgrade to LG K40.
For any queries or feedback, please leave a comment below.